1.
China
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China, officially the Peoples Republic of China, is a unitary sovereign state in East Asia and the worlds most populous country, with a population of over 1.381 billion. The state is governed by the Communist Party of China and its capital is Beijing, the countrys major urban areas include Shanghai, Guangzhou, Beijing, Chongqing, Shenzhen, Tianjin and Hong Kong. China is a power and a major regional power within Asia. Chinas landscape is vast and diverse, ranging from forest steppes, the Himalaya, Karakoram, Pamir and Tian Shan mountain ranges separate China from much of South and Central Asia. The Yangtze and Yellow Rivers, the third and sixth longest in the world, respectively, Chinas coastline along the Pacific Ocean is 14,500 kilometers long and is bounded by the Bohai, Yellow, East China and South China seas. China emerged as one of the worlds earliest civilizations in the basin of the Yellow River in the North China Plain. For millennia, Chinas political system was based on hereditary monarchies known as dynasties, in 1912, the Republic of China replaced the last dynasty and ruled the Chinese mainland until 1949, when it was defeated by the communist Peoples Liberation Army in the Chinese Civil War. The Communist Party established the Peoples Republic of China in Beijing on 1 October 1949, both the ROC and PRC continue to claim to be the legitimate government of all China, though the latter has more recognition in the world and controls more territory. China had the largest economy in the world for much of the last two years, during which it has seen cycles of prosperity and decline. Since the introduction of reforms in 1978, China has become one of the worlds fastest-growing major economies. As of 2016, it is the worlds second-largest economy by nominal GDP, China is also the worlds largest exporter and second-largest importer of goods. China is a nuclear weapons state and has the worlds largest standing army. The PRC is a member of the United Nations, as it replaced the ROC as a permanent member of the U. N. Security Council in 1971. China is also a member of numerous formal and informal multilateral organizations, including the WTO, APEC, BRICS, the Shanghai Cooperation Organization, the BCIM, the English name China is first attested in Richard Edens 1555 translation of the 1516 journal of the Portuguese explorer Duarte Barbosa. The demonym, that is, the name for the people, Portuguese China is thought to derive from Persian Chīn, and perhaps ultimately from Sanskrit Cīna. Cīna was first used in early Hindu scripture, including the Mahābhārata, there are, however, other suggestions for the derivation of China. The official name of the state is the Peoples Republic of China. The shorter form is China Zhōngguó, from zhōng and guó and it was then applied to the area around Luoyi during the Eastern Zhou and then to Chinas Central Plain before being used as an occasional synonym for the state under the Qing

2.
Meteorology
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Meteorology is a branch of the atmospheric sciences which includes atmospheric chemistry and atmospheric physics, with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not occur until the 18th century, the 19th century saw modest progress in the field after weather observation networks were formed across broad regions. Prior attempts at prediction of weather depended on historical data, Meteorological phenomena are observable weather events that are explained by the science of meteorology. Different spatial scales are used to describe and predict weather on local, regional, Meteorology, climatology, atmospheric physics, and atmospheric chemistry are sub-disciplines of the atmospheric sciences. Meteorology and hydrology compose the interdisciplinary field of hydrometeorology, the interactions between Earths atmosphere and its oceans are part of a coupled ocean-atmosphere system. Meteorology has application in diverse fields such as the military, energy production, transport, agriculture. The word meteorology is from Greek μετέωρος metéōros lofty, high and -λογία -logia -logy, varāhamihiras classical work Brihatsamhita, written about 500 AD, provides clear evidence that a deep knowledge of atmospheric processes existed even in those times. In 350 BC, Aristotle wrote Meteorology, Aristotle is considered the founder of meteorology. One of the most impressive achievements described in the Meteorology is the description of what is now known as the hydrologic cycle and they are all called swooping bolts because they swoop down upon the Earth. Lightning is sometimes smoky, and is then called smoldering lightning, sometimes it darts quickly along, at other times, it travels in crooked lines, and is called forked lightning. When it swoops down upon some object it is called swooping lightning, the Greek scientist Theophrastus compiled a book on weather forecasting, called the Book of Signs. The work of Theophrastus remained a dominant influence in the study of weather, in 25 AD, Pomponius Mela, a geographer for the Roman Empire, formalized the climatic zone system. According to Toufic Fahd, around the 9th century, Al-Dinawari wrote the Kitab al-Nabat, ptolemy wrote on the atmospheric refraction of light in the context of astronomical observations. St. Roger Bacon was the first to calculate the size of the rainbow. He stated that a rainbow summit can not appear higher than 42 degrees above the horizon, in the late 13th century and early 14th century, Kamāl al-Dīn al-Fārisī and Theodoric of Freiberg were the first to give the correct explanations for the primary rainbow phenomenon. Theoderic went further and also explained the secondary rainbow, in 1716, Edmund Halley suggested that aurorae are caused by magnetic effluvia moving along the Earths magnetic field lines. In 1441, King Sejongs son, Prince Munjong, invented the first standardized rain gauge and these were sent throughout the Joseon Dynasty of Korea as an official tool to assess land taxes based upon a farmers potential harvest. In 1450, Leone Battista Alberti developed a swinging-plate anemometer, and was known as the first anemometer, in 1607, Galileo Galilei constructed a thermoscope

3.
Satellite
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In the context of spaceflight, a satellite is an artificial object which has been intentionally placed into orbit. Such objects are called artificial satellites to distinguish them from natural satellites such as Earths Moon. In 1957 the Soviet Union launched the worlds first artificial satellite, since then, about 6,600 satellites from more than 40 countries have been launched. According to a 2013 estimate,3,600 remained in orbit, of those, about 1,000 were operational, the rest have lived out their useful lives and become space debris. Approximately 500 operational satellites are in orbit,50 are in medium-Earth orbit. A few large satellites have been launched in parts and assembled in orbit. Over a dozen space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Mercury, Venus, Mars, Jupiter, Saturn, a few asteroids, Satellites are used for many purposes. Common types include military and civilian Earth observation satellites, communications satellites, navigation satellites, weather satellites, Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, well-known classes include low Earth orbit, polar orbit, and geostationary orbit. A launch vehicle is a rocket that throws a satellite into orbit, usually it lifts off from a launch pad on land. Some are launched at sea from a submarine or a mobile maritime platform, Satellites are usually semi-independent computer-controlled systems. Satellite subsystems attend many tasks, such as power generation, thermal control, telemetry, attitude control, the first fictional depiction of a satellite being launched into orbit was a short story by Edward Everett Hale, The Brick Moon. The idea surfaced again in Jules Vernes The Begums Fortune, in 1903, Konstantin Tsiolkovsky published Exploring Space Using Jet Propulsion Devices, which is the first academic treatise on the use of rocketry to launch spacecraft. He calculated the speed required for a minimal orbit. In 1928, Herman Potočnik published his book, The Problem of Space Travel — The Rocket Motor. He described the use of orbiting spacecraft for observation of the ground, in a 1945 Wireless World article, the English science fiction writer Arthur C. Clarke described in detail the possible use of communications satellites for mass communications. He suggested that three geostationary satellites would provide coverage over the entire planet, the first artificial satellite was Sputnik 1, launched by the Soviet Union on October 4,1957, and initiating the Soviet Sputnik program, with Sergei Korolev as chief designer. This in turn triggered the Space Race between the Soviet Union and the United States, Sputnik 1 helped to identify the density of high atmospheric layers through measurement of its orbital change and provided data on radio-signal distribution in the ionosphere

4.
Agriculture
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Agriculture is the cultivation and breeding of animals, plants and fungi for food, fiber, biofuel, medicinal plants and other products used to sustain and enhance human life. Agriculture was the key development in the rise of human civilization. The study of agriculture is known as agricultural science, the history of agriculture dates back thousands of years, and its development has been driven and defined by greatly different climates, cultures, and technologies. Industrial agriculture based on large-scale monoculture farming has become the dominant agricultural methodology, genetically modified organisms are an increasing component of agriculture, although they are banned in several countries. Agricultural food production and water management are increasingly becoming global issues that are fostering debate on a number of fronts, the major agricultural products can be broadly grouped into foods, fibers, fuels, and raw materials. Specific foods include cereals, vegetables, fruits, oils, meats, fibers include cotton, wool, hemp, silk and flax. Raw materials include lumber and bamboo, other useful materials are also produced by plants, such as resins, dyes, drugs, perfumes, biofuels and ornamental products such as cut flowers and nursery plants. The word agriculture is a late Middle English adaptation of Latin agricultūra, from ager, field, Agriculture usually refers to human activities, although it is also observed in certain species of ant, termite and ambrosia beetle. To practice agriculture means to use resources to produce commodities which maintain life, including food, fiber, forest products, horticultural crops. This definition includes arable farming or agronomy, and horticulture, all terms for the growing of plants, even then, it is acknowledged that there is a large amount of knowledge transfer and overlap between silviculture and agriculture. In traditional farming, the two are often combined even on small landholdings, leading to the term agroforestry, Agriculture began independently in different parts of the globe, and included a diverse range of taxa. At least 11 separate regions of the Old and New World were involved as independent centers of origin, wild grains were collected and eaten from at least 105,000 years ago. Pigs were domesticated in Mesopotamia around 15,000 years ago, rice was domesticated in China between 13,500 and 8,200 years ago, followed by mung, soy and azuki beans. Sheep were domesticated in Mesopotamia between 13,000 and 11,000 years ago. From around 11,500 years ago, the eight Neolithic founder crops, emmer and einkorn wheat, hulled barley, peas, lentils, bitter vetch, chick peas and flax were cultivated in the Levant. Cattle were domesticated from the aurochs in the areas of modern Turkey. In the Andes of South America, the potato was domesticated between 10,000 and 7,000 years ago, along with beans, coca, llamas, alpacas, sugarcane and some root vegetables were domesticated in New Guinea around 9,000 years ago. Sorghum was domesticated in the Sahel region of Africa by 7,000 years ago, cotton was domesticated in Peru by 5,600 years ago, and was independently domesticated in Eurasia at an unknown time

5.
Forestry
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Forestry is the science and craft of creating, managing, using, conserving, and repairing forests and associated resources to meet desired goals, needs, and values for human and environment benefits. Forestry is practiced in plantations and natural stands, the science of forestry has elements that belong to the biological, physical, social, political and managerial sciences. A practitioner of forestry is known as a forester, other terms are used a verderer and a silviculturalist being common ones. Silviculture is narrower than forestry, being concerned only with forest plants, Forest ecosystems have come to be seen as the most important component of the biosphere, and forestry has emerged as a vital applied science, craft, and technology. Forestry is an important economic segment in various industrial countries, the preindustrial age has been dubbed by Werner Sombart and others as the wooden age, as timber and firewood were the basic resources for energy, construction and housing. The development of forestry is closely connected with the rise of capitalism, economy as a science and varying notions of land use. Roman Latifundiae, large estates, were quite successful in maintaining the large supply of wood that was necessary for the Roman Empire. Large deforestations came with respectively after the decline of the Romans, however already in the 5th century, monks in the then Byzantine Romagna on the Adriatic coast, were able to establish stone pine plantations to provide fuelwood and food. This was the beginning of the massive forest mentioned by Dante Alighieri in his 1308 poem Divine Comedy, the use and management of many forest resources has a long history in China as well, dating back to the Han Dynasty and taking place under the landowning gentry. A similar approach was used in Japan and it was also later written about by the Ming Dynasty Chinese scholar Xu Guangqi. In Europe, land rights in medieval and early modern times allowed different users to access forests. The notion of commons refers to the traditional legal term of common land. The idea of enclosed private property came about during modern times, however, most hunting rights were retained by members of the nobility which preserved the right of the nobility to access and use common land for recreation, like fox hunting. Systematic management of forests for a yield of timber is said to have begun in the German states in the 14th century, e. g. in Nuremberg. Typically, a forest was divided into sections and mapped. Large firs in the black forest were called „Holländer“, as they were traded to the Dutch ship yards, large timber rafts on the Rhine were 200 to 400m in length, 40m in width and consisted of several thousand logs. The crew consisted of 400 to 500 men, including shelter, bakeries, ovens, timber rafting infrastructure allowed for large interconnected networks all over continental Europe and is still of importance in Finland. The notion of Nachhaltigkeit, sustainability in forestry, is connected to the work of Hans Carl von Carlowitz

6.
Aviation
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Aviation is the practical aspect or art of aeronautics, being the design, development, production, operation and use of aircraft, especially heavier than air aircraft. The word aviation was coined by French writer and former naval officer Gabriel La Landelle in 1863, from the verb avier, itself derived from the Latin word avis and the suffix -ation. The modern age of aviation began with the first untethered human lighter-than-air flight on November 21,1783, the practicality of balloons was limited because they could only travel downwind. It was immediately recognized that a steerable, or dirigible, balloon was required, jean-Pierre Blanchard flew the first human-powered dirigible in 1784 and crossed the English Channel in one in 1785. Rigid airships became the first aircraft to transport passengers and cargo over great distances, the best known aircraft of this type were manufactured by the German Zeppelin company. The most successful Zeppelin was the Graf Zeppelin and it flew over one million miles, including an around-the-world flight in August 1929. However, the dominance of the Zeppelins over the airplanes of that period, the Golden Age of the airships ended on May 6,1937 when the Hindenburg caught fire, killing 36 people. The cause of the Hindenburg accident was blamed on the use of hydrogen instead of helium as the lift gas. An internal investigation by the manufacturer revealed the coating used to protect the material over the frame was highly flammable. Changes to the coating formulation reduced the risk of further Hindenburg type accidents, although there have been periodic initiatives to revive their use, airships have seen only niche application since that time. In 1799 Sir George Cayley set forth the concept of the airplane as a fixed-wing flying machine with separate systems for lift, propulsion. Seven years later, on 14 October 1897, Aders Avion III was tested without success in front of two officials from the French War ministry, the report on the trials was not publicized until 1910, as they had been a military secret. In November 1906 Ader claimed to have made a flight on 14 October 1897. Although widely believed at the time, these claims were later discredited, however, the most widely accepted date is December 17,1903 by the Wright brothers. The Wright brothers were the first to fly in a powered and controlled aircraft, previous flights were gliders or free flight, but the Wright brothers combined both, setting the new standard in aviation records. Aircraft began to transport people and cargo as designs grew larger, the Wright brothers took aloft the first passenger, Charles Furnas, one of their mechanics, on May 14,1908. By the beginning of World War II, many towns and cities had built airports, the war brought many innovations to aviation, including the first jet aircraft and the first liquid-fueled rockets. Manufacturers such as Cessna, Piper, and Beechcraft expanded production to provide aircraft for the new middle-class market

7.
Navigation
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Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another. The field of navigation includes four categories, land navigation, marine navigation, aeronautic navigation. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks, all navigational techniques involve locating the navigators position compared to known locations or patterns. Navigation, in a sense, can refer to any skill or study that involves the determination of position and direction. In this sense, navigation includes orienteering and pedestrian navigation, for information about different navigation strategies that people use, visit human navigation. In the European medieval period, navigation was considered part of the set of seven mechanical arts, early Pacific Polynesians used the motion of stars, weather, the position of certain wildlife species, or the size of waves to find the path from one island to another. Maritime navigation using scientific instruments such as the mariners astrolabe first occurred in the Mediterranean during the Middle Ages, the perfecting of this navigation instrument is attributed to Portuguese navigators during early Portuguese discoveries in the Age of Discovery. Open-seas navigation using the astrolabe and the compass started during the Age of Discovery in the 15th century, the Portuguese began systematically exploring the Atlantic coast of Africa from 1418, under the sponsorship of Prince Henry. In 1488 Bartolomeu Dias reached the Indian Ocean by this route, in 1492 the Spanish monarchs funded Christopher Columbuss expedition to sail west to reach the Indies by crossing the Atlantic, which resulted in the Discovery of America. In 1498, a Portuguese expedition commanded by Vasco da Gama reached India by sailing around Africa, soon, the Portuguese sailed further eastward, to the Spice Islands in 1512, landing in China one year later. The fleet of seven ships sailed from Sanlúcar de Barrameda in Southern Spain in 1519, crossed the Atlantic Ocean, some ships were lost, but the remaining fleet continued across the Pacific making a number of discoveries including Guam and the Philippines. By then, only two galleons were left from the original seven, the Victoria led by Elcano sailed across the Indian Ocean and north along the coast of Africa, to finally arrive in Spain in 1522, three years after its departure. The Trinidad sailed east from the Philippines, trying to find a path back to the Americas. He arrived in Acapulco on October 8,1565, the term stems from 1530s, from Latin navigationem, from navigatus, pp. of navigare to sail, sail over, go by sea, steer a ship, from navis ship and the root of agere to drive. Roughly, the latitude of a place on Earth is its angular distance north or south of the equator, latitude is usually expressed in degrees ranging from 0° at the Equator to 90° at the North and South poles. The height of Polaris in degrees above the horizon is the latitude of the observer, similar to latitude, the longitude of a place on Earth is the angular distance east or west of the prime meridian or Greenwich meridian. Longitude is usually expressed in degrees ranging from 0° at the Greenwich meridian to 180° east and west, sydney, for example, has a longitude of about 151° east. New York City has a longitude of 74° west, for most of history, mariners struggled to determine longitude

8.
Environmental protection
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Environmental protection is a practice of protecting the natural environment on individual, organisation controlled or governmental levels, for the benefit of both the environment and humans. Due to the pressures of over consumption, population and technology and this has been recognized, and governments have begun placing restraints on activities that cause environmental degradation. Since the 1960s, activity of environmental movements has created awareness of the environmental issues. There is no agreement on the extent of the impact of human activity and even scientific dishonesty occurs. For instance, in India, Environment Improvement Trust has been working for environment & forest protection since 1998, a group of Green Volunteers get a goal of Green India Clean India concept. CA Gajendra Kumar Jain an Chartered Accountant is founder of Environment Improvement Trust in Sojat city a small village of State of Rajasthan in India, in developing countries, such as throughout Latin America, these agreements are more commonly used to remedy significant levels of non-compliance with mandatory regulation. The challenges that exist with these agreements lie in establishing baseline data, targets, due to the difficulties inherent in evaluating effectiveness, their use is often questioned and, indeed, the whole environment may well be adversely affected as a result. The key advantage of their use in developing countries is that their use helps to build environmental management capacity and this approach ideally supports a better exchange of information, development of conflict-resolution strategies and improved regional conservation. Many of the resources are especially vulnerable because they are influenced by human impacts across many countries. As a result of this, many attempts are made by countries to develop agreements that are signed by multiple governments to prevent damage or manage the impacts of human activity on natural resources. This can include agreements that impact factors such as climate, oceans, rivers and these agreements have a long history with some multinational agreements being in place from as early as 1910 in Europe, America and Africa. Some of the most well-known international agreements include the Kyoto Protocol, discussion concerning environmental protection often focuses on the role of government, legislation, and law enforcement. However, in its broadest sense, environmental protection may be seen to be the responsibility of all the people, decisions that impact the environment will ideally involve a broad range of stakeholders including industry, indigenous groups, environmental group and community representatives. Gradually, environmental decision-making processes are evolving to reflect this broad base of stakeholders and are becoming more collaborative in many countries, many constitutions acknowledge the fundamental right to environmental protection and many international treaties acknowledge the right to live in a healthy environment. Also, many countries have organizations and agencies devoted to environmental protection, there are international environmental protection organizations, such as the United Nations Environment Programme. Tanzania is recognised as having some of the greatest biodiversity of any African country, almost 40% of the land has been established into a network of protected areas, including several national parks. In year 1948, Serengeti was officially established as the first national park for wild cats in East Africa, in 1998 Environment Improvement Trust start working for environment & forest protection in India from a small city Sojat. Founder of Environment Improvement Trust is CA Gajendra Kumar Jain working with volunteers, division of the biosphere is the main government body that oversees protection

9.
Rain
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Rain is liquid water in the form of droplets that have condensed from atmospheric water vapor and then precipitated—that is, become heavy enough to fall under gravity. Rain is a component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides suitable conditions for many types of ecosystems, as well as water for power plants. The major cause of production is moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts. If enough moisture and upward motion is present, precipitation falls from convective clouds such as cumulonimbus which can organize into narrow rainbands. On the leeward side of mountains, desert climates can exist due to the dry air caused by downslope flow which causes heating and drying of the air mass, the movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes. The urban heat island effect leads to increased rainfall, both in amounts and intensity, downwind of cities, global warming is also causing changes in the precipitation pattern globally, including wetter conditions across eastern North America and drier conditions in the tropics. The globally averaged annual precipitation over land is 715 mm, climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Rainfall is measured using rain gauges, rainfall amounts can be estimated by weather radar. Rain is also known or suspected on other planets, where it may be composed of methane, neon, sulfuric acid, or even iron rather than water. Air contains water vapor, and the amount of water in a mass of dry air. The amount of moisture in air is commonly reported as relative humidity. How much water vapor a parcel of air can contain before it becomes saturated, warmer air can contain more water vapor than cooler air before becoming saturated. Therefore, one way to saturate a parcel of air is to cool it, the dew point is the temperature to which a parcel must be cooled in order to become saturated. There are four mechanisms for cooling the air to its dew point, adiabatic cooling, conductive cooling, radiational cooling. Adiabatic cooling occurs when air rises and expands, the air can rise due to convection, large-scale atmospheric motions, or a physical barrier such as a mountain. Conductive cooling occurs when the air comes into contact with a surface, usually by being blown from one surface to another. Radiational cooling occurs due to the emission of infrared radiation, either by the air or by the surface underneath, evaporative cooling occurs when moisture is added to the air through evaporation, which forces the air temperature to cool to its wet-bulb temperature, or until it reaches saturation

10.
Thunderstorm
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Thunderstorms occur in association with a type of cloud known as a cumulonimbus. They are usually accompanied by winds, heavy rain, and sometimes snow, sleet, hail, or, in contrast. Thunderstorms may line up in a series or become a rainband, strong or severe thunderstorms, known as supercells, rotate as do cyclones. Thunderstorms result from the upward movement of warm, moist air. As the warm, moist air moves upward, it cools, condenses, as the rising air reaches its dew point temperature, water vapor condenses into water droplets or ice, reducing pressure locally within the thunderstorm cell. Any precipitation falls the long distance through the clouds towards the Earths surface, as the droplets fall, they collide with other droplets and become larger. Thunderstorms can form and develop in any location but most frequently within the mid-latitude. Thunderstorms are responsible for the development and formation of many weather phenomena. Thunderstorms, and the phenomena that occur along them, pose great hazards. Damage that results from thunderstorms is mainly inflicted by downburst winds, large hailstones, stronger thunderstorm cells are capable of producing tornadoes and waterspouts. There are four types of thunderstorms, single-cell, multi-cell cluster, multi-cell lines, supercell thunderstorms are the strongest and the most associated with severe weather phenomena. Mesoscale convective systems formed by vertical wind shear within the tropics and subtropics can be responsible for the development of hurricanes. Dry thunderstorms, with no precipitation, can cause the outbreak of wildfires from the heat generated from the lightning that accompanies them. Several means are used to study thunderstorms, weather radar, weather stations, past civilizations held various myths concerning thunderstorms and their development as late as the 18th century. Beyond the Earths atmosphere, thunderstorms have also observed on the planets of Jupiter, Saturn, Neptune. Warm air has a lower density than air, so warmer air rises upwards. Clouds form as relatively warmer air, carrying moisture, rises within cooler air, the moist air rises, and, as it does so, it cools and some of the water vapor in that rising air condenses. If enough instability is present in the atmosphere, this process will continue long enough for cumulonimbus clouds to form and produce lightning, Meteorological indices such as convective available potential energy and the lifted index can be used to assist in determining potential upward vertical development of clouds

11.
Hail
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Hail is a form of solid precipitation. It is distinct from ice pellets, though the two are often confused and it consists of balls or irregular lumps of ice, each of which is called a hailstone. Ice pellets falls generally in cold weather while hail growth is inhibited during cold surface temperatures. Unlike graupel, which is made of rime, and ice pellets, the METAR reporting code for hail 5 mm or greater is GR, while smaller hailstones and graupel are coded GS. Hail is possible within most thunderstorms as it is produced by cumulonimbus, Hail formation requires environments of strong, upward motion of air with the parent thunderstorm and lowered heights of the freezing level. In the mid-latitudes, hail forms near the interiors of continents, while in the tropics, there are methods available to detect hail-producing thunderstorms using weather satellites and weather radar imagery. Severe weather warnings are issued for hail when the stones reach a size, as it can cause serious damage to human-made structures and, most commonly. Any thunderstorm which produces hail that reaches the ground is known as a hailstorm, Hail has a diameter of 5 millimetres or more. Hailstones can grow to 15 centimetres and weigh more than 0.5 kilograms, unlike ice pellets, hailstones are layered and can be irregular and clumped together. Although the diameter of hail is varied, in the United States, stones larger than 2 cm are usually considered large enough to cause damage. The Meteorological Service of Canada issues severe thunderstorm warnings when hail that size or above is expected, the US National Weather Service has a 2.5 cm or greater in diameter threshold, effective January 2010, an increase over the previous threshold of ¾-inch hail. Other countries have different thresholds according local sensitivity to hail, for grape growing areas could be adversely impacted by smaller hailstones. Hailstones can be large or very small, depending on how strong the updraft is. These types of strong updrafts can also indicate the presence of a tornado, the growth rate is maximized where air is near a temperature of −13 °C. Like other precipitation in clouds, hail begins as water droplets. As the droplets rise and the temperature goes below freezing, they become supercooled water, a cross-section through a large hailstone shows an onion-like structure. This means the hailstone is made of thick and translucent layers, alternating layers that are thin, white. Former theory suggested that hailstones were subjected to multiple descents and ascents, falling into a zone of humidity and this up and down motion was thought to be responsible for the successive layers of the hailstone

12.
NASA
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President Dwight D. Eisenhower established NASA in 1958 with a distinctly civilian orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29,1958, disestablishing NASAs predecessor, the new agency became operational on October 1,1958. Since that time, most US space exploration efforts have led by NASA, including the Apollo Moon landing missions, the Skylab space station. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the agency is also responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA shares data with various national and international such as from the Greenhouse Gases Observing Satellite. Since 2011, NASA has been criticized for low cost efficiency, from 1946, the National Advisory Committee for Aeronautics had been experimenting with rocket planes such as the supersonic Bell X-1. In the early 1950s, there was challenge to launch a satellite for the International Geophysical Year. An effort for this was the American Project Vanguard, after the Soviet launch of the worlds first artificial satellite on October 4,1957, the attention of the United States turned toward its own fledgling space efforts. This led to an agreement that a new federal agency based on NACA was needed to conduct all non-military activity in space. The Advanced Research Projects Agency was created in February 1958 to develop technology for military application. On July 29,1958, Eisenhower signed the National Aeronautics and Space Act, a NASA seal was approved by President Eisenhower in 1959. Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA, earlier research efforts within the US Air Force and many of ARPAs early space programs were also transferred to NASA. In December 1958, NASA gained control of the Jet Propulsion Laboratory, NASA has conducted many manned and unmanned spaceflight programs throughout its history. Some missions include both manned and unmanned aspects, such as the Galileo probe, which was deployed by astronauts in Earth orbit before being sent unmanned to Jupiter, the experimental rocket-powered aircraft programs started by NACA were extended by NASA as support for manned spaceflight. This was followed by a space capsule program, and in turn by a two-man capsule program. This goal was met in 1969 by the Apollo program, however, reduction of the perceived threat and changing political priorities almost immediately caused the termination of most of these plans. NASA turned its attention to an Apollo-derived temporary space laboratory, to date, NASA has launched a total of 166 manned space missions on rockets, and thirteen X-15 rocket flights above the USAF definition of spaceflight altitude,260,000 feet. The X-15 was an NACA experimental rocket-powered hypersonic research aircraft, developed in conjunction with the US Air Force, the design featured a slender fuselage with fairings along the side containing fuel and early computerized control systems